The production of methanesulfonamide or its homologues such as ethane- or butane-sulfonamide by reacting methanesulfonyl chloride or its corresponding homologue with ammonia or with a primary or secondary amine is known. Ammonium chloride or an amine hydrochloride, as the case may be, is formed as by-product.
Consequently the accomplishment of this reaction, generally between 10.degree. and 90.degree. C. and usually between 50.degree. and 70.degree. C., in the presence of some liquid diluents such as alcohols, water, optionally chlorinated aliphatic or aromatic hydrocarbons such as methylene chloride and dichloroethane has already been recommended. On the basis of this approach, the French patent application No. 2,010,654 proposes C.sub.1 -C.sub.4 nitroalkanes as diluent.
According to the prior art, the alkanesulfonyl chloride is first dissolved in the diluent and the ammonia or the amine is then introduced into the liquid medium. The above-mentioned French patent application recommends the use of only a slight excess of ammonia or of amine, i.e., only until a slight basicity of the reaction medium is observed.
However, this procedure has severe disadvantages. First of all, its leads to an amide containing various undesirable by-products which are detrimental to the purity of the usable product. For ammonia as the nitrogen-containing reagent, the formation, inter alia, of dialkyldisulfonamide R--SO.sub.2 --NH--SO.sub.2 --R, is observed, this involves a wasteful consumption of starting materials, which is unfavorable for achieving a good alkanesulfonamide yield, not to mention additional problems of separation caused by the presence of these by-products.
Additionally, during the separation and recovery of the alkanesulfonamide sought, the reaction mixture must be heated, for example between approximately 50.degree. and 80.degree. C., especially when the actual reaction has been carried out at temperatures below 50.degree. C. The purpose of this heating is to solubilize any alkane-sulfonamide remaining in the form of a precipitate, in the diluent, mixed with the by-product ammonium chloride or amine hydrochloride. This is especially recommended in French patent application No. 2,010,654.
Additionally, the diluents proposed for performing the reaction are unsatisfactory in many respects. Indeed, the nitroalkanes of the above-mentioned publication have inadequate solubility properties at ambient temperature towards alkanesulfonamides. As just mentioned, this makes it necessary to maintain a temperature of at least 50.degree. C. to solubilize the maximum possible amount of alkanesulfonamide. Additionally, it is known that nitroalkanes are solvents which are expensive and difficult to use because of their fairly wide explosibility limits. For example, those for nitromethane are between 7.3 and 63%.
The alcohols, on their part, as they are not sufficiently chemically inert, do not constitute suitable media because they give rise to the formation of dialkyl ehters and alkanesulfonic acid esters as interfering products. Additionally, the by-product, which consists of the amine hydrochloride, is soluble in alcohols. This prevents it from being separated easily, for example, by simply filtering or centrifuging.
Water as diluent gives a quantity of ammonium alkanesulfonate which is not insignificant and which is undesirable.
Finally, the use of optionally chlorinated aliphatic or aromatic hydrocarbons has the disadvantage of maintaining the alkanesulfonamides as well as the by-product salts in an insoluble form. Because of this, the reaction products cannot be separated by simple means of filtration or centrifugation.